NUTRIENT UPTAKE,PHYSIOLOGICAL RESPONSES,AND YIELD ATTRIBUTES OF WHEAT (TRITICUM AESTIVUM L.) EXPOSED TO EARLY AND LATE DROUGHT STRESS

The response of different wheat cultivars to drought imposed after three and six weeks of seedling emergence was evaluated in the wire house. The seeds of recommended local wheat cultivars were sown in plastic pots. The drought stress decreased the water relation, nutrient uptake and grain yield of all the wheat cultivars. The early drought stress significantly reduced the nitrogen (N) uptake by 38% while late drought stress decreased nitrogen uptake by 46%. The phosphorus (P) and potassium (K) uptake were decreased by 49% and 37% under early drought stress, respectively while their uptake was decreased by 51% each under late drought stress. Grain yield was reduced by 24% under early drought stress while it was reduced by 60% under late drought stress. Water deficit at early growth stages reduced grain weight by 10% while it was reduced by 35% under water deficit at later stages of growth.     

基于多源遥感数据的综合干旱监测模型构建

在全球气候变化越来越复杂的大背景下,准确监测华北粮食主产区的旱情对区域农业生产有重要的指导意义。以往的遥感干旱监测方法多侧重于监测土壤或植被等单一干旱响应因子,反映综合信息的能力较差,为此该研究使用中分辨率成像光谱仪(moderate-resolution imaging spectroradiometer,MODIS)、热带降水测量计划(tropical rainfall measuring mission,TRMM)卫星等多源遥感数据,在综合考虑干旱发生发展过程中的土壤水分胁迫、植被生长状态和气象降水盈亏等因素的基础上,利用空间数据挖掘技术,构建综合干旱监测模型,并以山东省为例进行了试验验证。结果表明,模型监测出山东省近年来所经历的重大干旱过程与实际旱情一致,模型输出的旱情指标-综合干旱指数(synthesized drought index,SDI)与小麦的标准化作物单产变量的相关系数均大于0.7(P0.05);在小麦和玉米的生长期,综合干旱指数与作物受灾面积的相关系数在-0.67～-0.85之间,与标准化降水指数(standardized precipitation index,SPI)的相关系数在0.44～0.67之间,且通过了P0.01的极显著检验(3月份除外)。研究结果为综合评估区域干旱提供了一种新的方法。     

看麦娘叶片对化感小麦根水提液的生理响应

为阐明小麦化感抑草的生理机制,选择强化感小麦‘115/青海麦’、‘92L89’和弱化感小麦‘抗10103’,通过添加浓度为0.2%、0.5%和1.0%的小麦根水提液进行水培试验3周后,测定了各处理看麦娘的鲜重,分析叶片中叶绿素(SPAD值)、可溶蛋白、MDA、类黄酮、总酚的含量以及SOD、POD、CAT活性。结果表明,水提液处理显著抑制了看麦娘的生长,抑制率在不同处理浓度及小麦品种间均存在显著差异,强化感小麦的抑制率显著高于弱化感小麦。在处理浓度范围内,不同小麦根水提液的抑制率大小依次为‘115/青海麦’(24.7%~74.3%)‘92L89’(15.7%~71.6%)‘抗10103’(13.8%~61.4%);0.2%、1.0%和5.0%水提液处理的抑制率大小依次为13.8%~24.7%、41.7%~66.4%和61.4%~74.2%。看麦娘叶绿素含量(SPAD值)随处理浓度增大显著降低,可溶蛋白含量,SOD、POD、CAT活性,MDA、类黄酮含量随处理浓度增大显著升高,强化感小麦对看麦娘的生理刺激作用高于弱化感小麦。1.0%‘115/青海麦’及5.0%各小麦水提液处理的看麦娘总酚含量高于对照。可见,小麦化感胁迫提高了看麦娘的保护酶系统活性,增强了抗氧化物质代谢,但显著增强了细胞膜脂质过氧化和叶绿素降解,不利于靶标植物看麦娘的生长。     

Effects of nitrogen feeding for extraradical mycelium of Rhizophagus irregularis maize symbiosis incorporated with phosphorus availability

In terrestrial ecosystems, plants are frequently in symbiosis with arbuscular mycorrhizal fungi (AMF) with mineral nutrients and photosynthesis carbon exchanges in between. This research sought to identify the effects of phosphorus (P) levels on the nitrogen (N) uptake via extraradical mycelium (ERM) and the mycorrhizal growth response (MGR) of maize plants within the AMF symbiosis. Pots were separated into root compartments and hyphae compartments (HCs) with two layers of a 30‐μm mesh membrane and an air gap in between, where only hyphae could pass through, to avoid both N diffusion and root growth effects. Maize plants were inoculated with Rhizophagus irregularis with different N fertilization in HCs under two different P fertilization levels. Our results indicated that a strong increase in MGR with low‐P fertilization. The same tendency was not observed with high‐P fertilization, although both had a large increase in P concentration as a potential source of growth in shoot tissue of mycorrhizal plants. Substantial effects (10.5% more N) were observed in the case of high‐P availability for the host plants from ERM fed with N, whereas under low‐P conditions ERM may prioritize P uptake rather than N uptake. The AM fungi increase the uptake of N and P, which are most limiting in the soil with fewer forces from soil resources. In addition, there was still more P accumulated than N due to the high N for ERM with high‐P supply. Low N in HCs corresponded with a lower colonization rate in roots but with high hyphae density in HCs; this result suggest that N and P availability might change the ratio of extraradical to intraradical hyphae length.     

玉米皮多酚提取工艺优化及抗氧化性研究

为探究超声辅助酶解法提取玉米皮多酚的最优工艺,并探讨其体外抗氧化活性,以玉米皮多酚提取量为响应值,分别考察超声时间、提取温度、料液比和酶添加量4个因素对提取效果的影响。在单因素试验的基础上,采用中心组合响应面分析法对提取工艺进行优化。结果表明,最佳提取条件为:超声时间6.5 min、酶解温度55℃、液料比41 mL·g^-1、木聚糖酶添加量2.10%,此条件下,玉米皮多酚提取量最高,为7.26 ± 0.15 mg·g^-1,与响应面预测值7.17 mg·g^-1相近。DPPH·和ABTS⁺·清除法抗氧化试验结果表明,玉米皮多酚具有较强的抗氧化能力,可作为潜在天然抗氧化剂应用于食品行业。本研究结果为玉米加工副产物玉米皮综合应用提供了理论依据。     

基于SWAT模型的气候变化下水文响应分析——以福建省长汀县朱溪小流域为例

本文以长汀县河田地区朱溪小流域为研究区,基于多年的气象、水文数据及高程数据模型、土地利用图、土壤类型图等,构建朱溪小流域SWAT模型。本文在假设下垫面条件不变的情况下应用假定气候情景法,通过改变日最高、最低气温值和逐日降雨量值构建15种不同的气候条件情景定量模拟分析气候变化对朱溪小流域径流的影响。研究结果表明:降水和温度的变化共同影响着朱溪小流域的产流过程,朱溪小流域的径流量与降雨量呈现正相关关系,与气温呈现负相关关系;相对于温度变化对朱溪小流域径流的影响,降雨量对于研究区径流量的影响更大。     

2个不同耐旱性甘薯品种的苗期根系蛋白组差异分析

为从蛋白水平明确不同耐旱性甘薯品种苗期根系对干旱的应答机制,促进甘薯耐旱相关基因发掘,以耐旱性强的济薯21(JS)和耐旱性弱的济紫薯1(JZ)为材料,采用PEG-6000模拟田间梯度干旱胁迫过程,进行苗期根系蛋白的双向电泳和质谱分析。结果表明,基于60个不同耐旱性甘薯苗期根系的差异蛋白点分析,共鉴定出32个蛋白,其中有明确生理功能的有12个。在JZ中,下调表达的有3个肌动蛋白,上调表达的有2个60S核糖体蛋白,受体类蛋白激酶和真核翻译起始因子各1个;在JS中,下调表达的有1个类甜蛋白,上调表达的有2个过氧化物酶蛋白、1个磷酸果糖激酶家族蛋白和1个赤霉素调控蛋白。基因本体(GO)分析发现,干旱对甘薯苗期根系细胞质中糖和能量代谢过程影响较大,耐旱性强的品种苗期根系在抗氧化防御、能量代谢和信号转导方面占据优势。综上,不同耐旱性甘薯苗期根系在蛋白组学水平上响应干旱的生理调控途径存在明显差异,本研究结果为甘薯耐旱性品种选育提供了理论依据。     

酶解牦牛血发酵液制备抗氧化肽工艺优化

为进一步提高牦牛血枯草芽胞杆菌发酵液多肽含量,对牦牛血发酵液进行酶解,以酶解液的·OH清除率、多肽含量为主要指标,筛选酶解发酵液的最适蛋白酶,通过单因素和响应面试验优化酶解工艺,并对比菌酶联合制备产物与发酵液体外抗氧化活性。结果表明,碱性蛋白酶酶解发酵液最佳条件为:酶解时间3 h、p H值9.5、酶解温度60℃和酶底比190 U·g-1,此条件下制备得到酶解液多肽含量为5.52mg·mL~(-1),较发酵液提高2.39倍。菌酶联合制备产物对·O2-及脂质过氧化的IC50分别为6.22、4.87mg·mL~(-1),发酵法制备产物对·O2-及脂质过氧化的IC50分别为8.42、11.71 mg·mL~(-1),且菌酶联合制备产物的还原力优于发酵制备产物。因此,菌酶联合制备牦牛血抗氧化肽法优于传统单一发酵法。本研究结果对提高牦牛血抗氧化肽得率,增加牦牛产品附加值具有重要的意义。     

基于iTRAQ技术的不同耐旱性甘薯苗期根系差异蛋白分析

为从蛋白水平揭示不同甘薯品种的苗期耐旱性差异,明确甘薯耐旱性生理机制,以耐旱性强的济薯21(JS)和耐旱性弱的济紫薯1(JH)为材料,采用PEG-6000模拟田间梯度干旱胁迫过程,采用i TRAQ技术开展甘薯苗期根系全蛋白组差异蛋白分析。结果表明,在4个比较组中,共筛选到567个差异表达蛋白,其中上调表达蛋白302个,覆盖率达20%以上的蛋白占鉴定总蛋白数的58.6%。GO分析发现,JS苗期根系差异蛋白主要集中在胁迫响应、非生物刺激响应等生物过程,而JH苗期根系差异蛋白主要集中在糖基复合物代谢和辅酶代谢等生物过程,干旱均主要影响2个品种的细胞质、细胞溶质等细胞组分,2个品种的差异蛋白分子功能均涉及催化活性、氧化还原酶活性等方面。KEGG分析发现,正常条件下,耐旱性强的较耐旱性弱的甘薯品种苗期根系中的过氧化物酶(POD)和肉桂醇脱氢酶(CAD)表达上调;在干旱条件下,次生代谢合成过程中的苯丙烷合成通路中上调表达的差异蛋白最多,耐旱性强的JS苗期根系中主要是胁迫响应相关蛋白,而耐旱性弱的JH苗期根系中主要是能量代谢相关蛋白。总之,干旱对甘薯苗期根系细胞质中次生物质合成和能量代谢影响较大,耐旱性强的甘薯苗期根系氧化还原酶类蛋白表达上调,不同耐旱性甘薯苗期根系在蛋白组学水平上响应干旱的生理调控途径存在明显差异。本研究为甘薯耐旱性品种生理鉴定和耐旱基因发掘提供了线索。